Think about it, what are taxes for? To pay for all the things we share as a people: government, roads, healthcare etc.
If we're getting an equal amount out of the system why is it fair to expect people to pay different amounts into that system. Think about it, If you go out for dinner with friends and all eat the same amount you wouldn't expect to pay the bill based on your incomes.
That's why if you really wanted a "fair" system everyone would pay a flat dollar rate, such as $5000/person. I realize that's not realistic but perhaps we could meet in the middle with a flat tax rate, which would mean rich people would be paying WAY more than poor people. Don't even get me started on tax brackets, you're taxing people for being successful? That's just legalized theft and beyond mental.
Also, why do we never question income tax? That's a relatively new invention, you're telling me I now have to pay money to make money and then ALSO to spend money? That's fucked up, it's double dipping by the government and it's immoral.
Bingo, you get it, that way people who consume more pay more tax and everyone wins